The descriptions in this section merely provide background information related to the present disclosure and may not constitute prior art.
Encoding a video involves an indication of a color format of the video expressed by the ratio of luminance signals to chrominance signals of pixels included in a horizontal pixel line of a component picture of the video. Typically, the luminance signals are expressed by Y signals and the chrominance signals are expressed by Cb/Cr signals.
Luminance represents the degree of brightness of an image, and ITU-R recommends using eight bits for indicating the luminance of an image. Chrominance is information to represent the color of an image by using two 8-bit values (Cb/Cr). A coordinate system for representing colors is called a color space where the color format of a video is expressed three pieces of 8-bit information of Y, Cb, and Cr according to the video encoding standard of Moving Picture Expert Group (MPEG).
The typical video compressing techniques such as MPEG-2, MPEG-4, JVT (Joint Video Team) are adapted to compress a video into 4:4:4 color format, 4:2:2 color format, and 4:2:0 color format of videos. These compressing techniques have set color formats in units of video sequences and have a shortcoming that they are incapable of compressing an image constituting the video in various color formats.